Artificial Insemination
By Dr Mackie Hobson BSc(Agric),BVSc

Ewes

1. Flush feed (if conditions are sub-optimal)
2. Dip 2 weeks before, cruch and dose (if required)
3. Insert CIDRS/Sponges  14-18 days (follow manufacturer’s guidelines RAMSEM)

CIDR Synchronisation sponges

 A: CIDR B: CIDR applicator C: Antibiotic cream

Ovacron Synchronisation sponges

A: Ovacron sponge B: Sponge Applicator C: Antibiotic cream

1. Sponges/CIDRS removed (if string is broken you will need something to remove the sponge)

orceps                                                                                               Farmer practical alternative

5. 200IU PMSG i/m (Chrono-Gest PMSG 6000IU) is injected intramuscularly when the sponges/CIDRS are removed.  Some farmers will use lower dose 150-180 (1.6ml of dilution) to try avoid multiple births. FOLLOW manufacturer’s guidelines which will be sent with your order.

This is a serum gonadotrophin and it works by stimulating the growth of the interstitial cells of the ovary as well as growth and maturation of the follicles. Due to its LH-activities PMSG also induces ovulation.

In rare cases an allergic reaction to the injection can occur

P.M.S.G A      A: sterile water B: PMSG

1. Introduce Teaser rams in for morning before the planned AI, remove them in afternoon (if you have teasers).
2. AI Maiden ewes 40-46 hrs. after CIDR removal

AI Mature ewes 44-48 hrs.  after CIDR removal

(Follow RAMSEM instructions)

1. No water overnight (reduce urination at time AI)

Rams

1. Fertility tested
2. Flush fed (if conditions are  sub-optimal)
3. Use alternate days to tap semen to allow recovery 

Equipment

Basic equipment consists of:

•  Speculum with a built in light source
• Pipette connected to a 1ml syringe. 

 The plastic disposable pipettes are popular. For sheep the tip is tapered over a flame and bent at about 30%. For goats penetration of the cervix is easier with a straight pipette.

A: syringe B: rubber connector C: Pipette for cervical insemination

SPECULUM: A: speculum head B: speculum hand head C: speculum lamp D: handle E/F: speculum tube (only one) E: plunger

Artificial Vagina assembled above and in pieces below                                       

 Collecting Tube A: Vagina T piece B: Rubber stopper C: Latex liner D: Collecting tube

Spares

Don’t forget spares. There can be nothing worse than going through this procedure and having the speculum bulb fail or batteries run flat!

SEMEN COLLECTION

Collect semen by:

1. Artificial Vagina   OR
2. Ejaculator

Collecting tube must be at body temperature 

Semen collection using an Ejaculator                       OR               Artificial Vagina

Once collected the semen must be kept warm by:

• Holding it in hand OR
• Water bath at 30-34C

Keep the top covered by a swab or tissue paper

Collected semen

AI METHOD:

Restraint of ewes:

(i) Placing the hindquarters over a rail with the head downwards. Height of the rail should be 80-90cm and the front legs should remain standing on the floor. OR

(ii) Elevating the hindquarters by having an assistant lift them manually.

Positioned over pole                                      OR                        Manually raised hindquarters

1. One assistant stands over ewe and secures the hind legs.
2. The vulva of the ewe is wiped with cotton wool or a tissue (this can also be done earlier).
3. The speculum with a bit of lubrication is carefully inserted into the vagina to a depth of 10-13cm.
4. The cervix opening is identified and located. A large variation in size and shape of cervix opening between females. In maiden ewes it is sometimes observed just as a split in the anterior vagina. In older ewes the cervix usually protrudes into the vagina and the opening of the cervix has to be found with the bent tip of the pipette between the folds of the cervix.

             Identify the Cervix

1. When a large amount of mucus has accumulated in the vagina or when mucus covers the cervix, the vagina should be drained. The assistant lifts the front end of the ewe up high and the mucus drains through the speculum tube.
2. Load the pipette.

• The plunger of the syringe is withdrawn to 0,2ml to have some air behind the semen.
• The appropriate amount of semen is drawn into the pipette 0.1-0.2ml) from the semen collection tube in a water bath at 30 °C-34°C or from the assistant holding the collecting tube at body temperature in his hand.

Assistant holding prepared pipette and collecting tube      Semen drawn into pipette

1.  The inseminator should attempt to introduce the pipette into the cervix without using force. Semen is deposited into the cervix by depressing the plunger of the syringe.  It may be easier for an assistant to press the plunger while you hold the pipette and the speculum.

• The speculum is withdrawn first and then the pipette to prevent backflow of the semen. In goats it is easier to achieve deep penetration into cervix than with sheep. Complete penetration can be felt by the lack of resistance. Avoid pushing the pipette by force too deep as this can cause damage to the cervix canal.

Pressing the syring plunger.                   You might find it easier to get an assistant to                               press plunger while you keep the pipette in cervix                                         

8. Instruments must be cleaned between inseminations. Speculum is wiped off between each ewe.  Pasteurised (boxed milk) can be used to rinse the speculum- keep the milk at 36C by placing the milk container in a second beaker to which hot water can be added- see below.

If mild disinfectant is used then rinse again in clean water as disinfectants are detrimental to semen.

AI Pipettes should be wiped with a quaze swap between ewes.

Speculum and plunger cleaned between inseminations 

Follow up identification of on heat ewes and mating

• 18-21 days after AI use teasers can be used to identify ewes in heat.
• Ewes detected in heat in the morning are caught out and put with the ram in the evening.
• Ewes detected in heat in the evening are caught out and put with the ram in the morning.

THEORY BEHIND THE AMOUNT OF SEMEN USED PER AI

Semen is evaluated for its appearance and motility. (SEE TABLES BELOW)

Appearance

This gives one an idea of the number of sperm per ml of semen.

Thick creamy would equate to roughly 3200 mil sperm/ml while thin milky would equate to 400 mil sperm/ml (see table)

Motility

% of mobile sperm is scored 0-5 under a microscope (10X) or eyepiece 

Viable sperm per ml of semen can then be calculated

For example  excellent  thick creamy semen with a motility score of 4 (80% )

• 3200 X 0.8 = 2560 million viable sperm per ml

For AI  50 – 100ml sperm are required so 0.1 ml sperm is more than sufficient. 

It is possible to dilute the semen to make it ‘go further’ when limited semen or larger numbers of ewes that need to be inseminated with a very valuable ram

• Require 500million sperm per ml to AI 0.1-0.2 mls
• Thick creamy semen 2560/500 = 5.1 (viable sperm per ml/number sperm required per ml)
• On average thick creamy semen  can be dilute 1: 4 with skimmed milk pasteurised (32C)
• Use 0.1 or 0.2 ml of this diluted semen  = 50-100mil sperm per AI

STICK TO PURE SPERM initially. Approximately 15-20 rams can be inseminated on the average amount of semen collected.

Dr Mackie Hobson

• For AI  50-100 mil sperm are needed

EXAMPLE

If thick creamy sample

              Calculate: sperm/ml X motility % (3200 x0.8 = 2560 viable sperm per ml)

Sponge ewes 14d (+/- 1-2d) inject 300IU PMSG at sponge removal. Increased ovulation if inj i/m and day before removal.

Collect artificial vagina (water 50-55C) 32C  in water

Inseminate 48/60/72 hrs (or fixed time 56 hrs after sponge removal)

In theory 50-100 million sperm are needed for AI.

Diluent for fresh semen at 30°C -34°C – Skim milk.

Sterilised cow skim milk or UHT skim milk (long life milk) is the most convenient diluent to use on farms. Conception depend on number of mobile spermatozoa and not on volume. Diluent used to extend life span of semen for 1-2 hours and to have a slighter higher volume for easier AI. Semen with density of cream to thick cream and motility of 5 and 4 can be diluted 1+2 to 1+3. Insemination dose 0,1ml/ewe. Thin cream semen with motility of  3 / 4 - diluted only 1+1. No problem if 0,5ml to 0,1ml of undiluted semen is put into ewes 0-20 minutes after collection.